I forsee an end to his Cub career at the end of this season.
He might be good for 15-18 starts this year. 5-6 of those will be good or really good, 5-6 of those will be decent, 5-6 of those will be just gawd awful. Good luck figuring out which ones are which beforehand.
Next year though, he is a HUGE sleeper. Since he will no longer be a Cub, he will start 30 games, win about 18 of them, and rack up about 275 K's in 220 IP.